The Robert H. Lurie Comprehensive Cancer Center Flow Cytometry Core Facility provides comprehensive flow cytometry and cell sorting services. The Flow Cytometry Core Facility serves investigators of the Cancer Center, Northwestern University Medical School, Northwestern University and other affiliated institutions by providing access to routine flow cytometry assays such as immunophenotyping and DNA analysis. However, research users encompass individuals with a broad spectrum of training in the basic and clinical sciences, and thus, a major goal of the facility is to provide the guidance, technical assistance, and equipment for investigators to utilize more complex multi-parametric, multi-laser measurements as well as cell sorting in their research regardless of their level of cytometry expertise. The equipment and expertise housed within the Core Facility permits implementation of most flow cytometry assays that have been published. Services provided by the facility personnel extend from consultation on experimental design, sample preparation and data analysis to instrument operation and set-up for cell-sorting and multi-laser operation. Because of the emphasis the facility places on the quality of data, the flow laboratory also offers services for sample preparation, data acquisition, and data analysis. In addition, the Core Facility has an active program of assay development guided by the interests of the investigators. As such, the Flow Cytometry Core Facility serves as a focus for individuals interested in cellular based measurements and cellular heterogeneity in disease providing critical support for cancer related research within the institution. This is also reflected by the Core Director's, and Cancer Center's, key founding involvement in the Cytometry Consortium, a multiinstitutional collaborative group focusing on complex multi-parametric cell based cytometry assay development in support of clinical trials and translational research. The facility includes two cell sorters; a five laser, 13 color MoFlo high speed cell sorter (Dako) and a two laser, six color Elite ESP (Beckman Coulter) cell sorter. In addition the facility has two benchtop flow cytometry analyzers; a 3 laser, 9 color Cyan (Dako) and a single laser, four color XL (Beckman Coulter). In addition, the flow lab has a ViCell cell .: counter/viability measurement instrument (Beckman Coulter) for cell line characterization and quality control for high speed sorting. In support of these instruments, the facility also has an offline analysis workstation providing the components for post acquisition data analysis and graphics generation. The Core Facility is now heavily utilized by a wide number of investigators (88), approximately 64.7% of which are Cancer Center members who account for approximately 73.0% of core utilization.